import React,{Component} from 'react'


export default class Count extends Component{

  //加
  increment = ()=>{
    const {value} = this.selectNumber
    this.props.jia(value*1)
  }
  //减
  decrement = ()=>{
    const {value} = this.selectNumber
    this.props.jian(value*1)
  }
  //奇数再加
  incrementIfOdd = ()=>{
    const {value} = this.selectNumber
    if(this.props.count%2 !== 0) this.props.jia(value*1)
  }
  //异步加
  incrementAsync = ()=>{
    const {value} = this.selectNumber
    this.props.asyncJia(value*1,500)
  }

  render(){
    return (
      <div>
        <h1>当前求和为：{this.props.count}</h1>
        <select ref={c => this.selectNumber = c}>
          <option value="1">1</option>
          <option value="2">2</option>
          <option value="3">3</option>
        </select><br />
        <button onClick={this.increment}>+</button>&nbsp;
        <button onClick={this.decrement}>-</button>&nbsp;
        <button onClick={this.incrementIfOdd}>当前求和为奇数再加</button>&nbsp;
        <button onClick={this.incrementAsync}>异步加</button>
      </div>
    )
  }
}